This invention relates to a bushing block. In one of its more specific aspects, this invention relates to means for minimizing temperature variations of liquid glass within a bushing.
The formation of glass fibers by drawing streams of glass from an apertured bushing is well known. In most instances, the glass is caused to flow from a melting source, through a bushing block and into a bushing. Streams of glass are drawn through the apertures thereof and are collected by winding as one or more packages on a collet driven by a winder.
It has been observed, particularly when two or more packages are being formed from fibers drawn from one bushing, that there can exist considerable variation in the diameter of fibers drawn from different areas of the bushing. This is attributable to a temperature imbalance between areas of the bushing block and hence, of the glass. As a result of this imbalance, there arise problems of yardage control, strand tension and package builds.
Measurements indicate that temperature variations of 100.degree. F., or more, can exist along the length of the bushing block at the interface between the bushing block and the bushing. Generally, bushings do not have the capacity of balancing temperature differences of this magnitude during the short residence time of the glass in the bushing.
The bushing block of this invention significantly reduces such temperature differentials within the bushing and, while particularly suitable for the production of two or more packages from the same bushing, can be used for single package production.